A known concealed flush tank has laterally integrally formed fishplates, to which a sheetmetal mounting frame is screwed. This flush tank is made by blow-molding, and the fishplates, extending essentially over the full height of the tank, require a complicated mold separation of the blow-molding die. To achieve secure attachment of the mounting frame, several screws must be applied, which requires substantial labor. The production risk and the number of possible cases of damage are comparatively high for this flush tank due to the relatively expensive manufacture and installation.
Known also is a flush tank on the outside of which fishplates are welded on by ultrasonics for attachment of a mounting frame. It has been found that even with very careful working the welding quality is irregular and crack formation at the flush tank is possible. The production risk and cost of inspection are therefore high also for this flush tank.
According to the present state of the art, therefore, there is a need of a flush tank or similar tank which avoids the cited disadvantages and which thus is easier to manufacture at lower production and inspection costs and can be attached on a mounting element, in particular a mounting frame.